Bayesian Logical Data Analysis for the Physical Sciences: References

In this paper, the problem of active fault tolerant control for a reusable launch vehicle (RLV) with actuator fault using both adaptive and sliding mode techniques is investigated. Firstly, the kinematic equations and dynamic equations of RLV are given, which represent the characteristics of RLV in reentry flight phase. For the dynamic model of RLV in faulty case, a fault detection scheme is proposed by designing a nonlinear fault detection observer. Then, an active fault tolerant tracking strategy for RLV attitude control systems is presented by making use of both adaptive control and sliding mode control techniques, which can guarantee the asymptotic output tracking of the closed-loop attitude control systems in spite of actuator fault. Finally, simulation results are given to demonstrate the effectiveness of the developed fault tolerant control scheme.

Active fault tolerant control design for reusable launch vehicle using adaptive sliding mode technique

Flight Vehicle System Identification: A Time-Domain MethodologyJategaonkarR. V., Progress in Aeronautics and Astronautics, 2nd ed., AIAA, Reston, VA, 2015, 648 pp., $119.95.

This paper presents a combined feedback and feedforward active load alleviation system and its associated design and tuning methodology The feedback part is strongly structured and its robust performance across the flight envelope is ensured by the use of a multi-model and multi-objective controller design approach The feedforward function is based on a Doppler LIDAR sensor and the processing of the measurements as well as their physical interpretation combines various ideas from the system identification, the signal processing, and the control design domains The proposed solution remains very easy to use and tune, thanks to a limited number of parameters that can easily be interpreted physically and that exhibit only very little and very predictable couplings The performance and behavior of the active load alleviation functions is shown extensively based on a representative flexible long range aircraft model (based on the Airbus XRF1 configuration)

/pdf/combined-feedback-and-lidar-based-feedforward-active-load-3uz7ffib43.pdf

Combined Feedback and LIDAR-Based Feedforward Active Load Alleviation

The low-biased, fast, airborne, short-range, and range-resolved determination of atmospheric wind speeds plays a key role in wake vortex and turbulence mitigation strategies and would improve flight safety, comfort, and economy. In this work, a concept for an airborne, UV, direct-detection Doppler wind lidar receiver is presented. A monolithic, tilted, field-widened, fringe-imaging Michelson interferometer (FWFIMI) combines the advantages of low angular sensitivity, high thermo-mechanical stability, independence of the specific atmospheric conditions, and potential for fast data evaluation. Design and integration of the FWFIMI into a lidar receiver concept are described. Simulations help to evaluate the receiver design and prospect sufficient performance under different atmospheric conditions.

/pdf/design-of-a-monolithic-michelson-interferometer-for-fringe-2v6i6pgyki.pdf

Design of a monolithic Michelson interferometer for fringe imaging in a near-field, UV, direct-detection Doppler wind lidar.

A new generic aircraft model called VIRTTAC-Castor is introduced. This model was developed by DLR and will be made available for the research community. VIRTTAC-Castor is the first member of a complete model family available in the future. The "VIRtual TesT AirCraft" models will consist of several aircraft designs of different sizes and configurations to be used for manifold applications. Each model of the VIRTTAC family can be utilized for virtual flight test just as engineers would perform with a real aircraft. The VIRTTAC family is designed to provide high-quality validation benchmark models for e.g. system identification, controller design and demonstration of fault-tolerant controllers as well as reduced envelope protection functions.

/pdf/virttac-a-family-of-virtual-test-aircraft-for-use-in-flight-42elffzx0g.pdf

VIRTTAC - A Family of Virtual Test Aircraft for Use in Flight Mechanics and GNC Benchmarks

Robust LPV control design for a RLV during reentry

This paper presents an unusual feedforward controller structure that allows to take allocation constraints into account which can be expressed in the time-frequency or time-scale domains. This novel controller structure was motivated by the design of a feedforward controller for airplane gust and turbulence load alleviation based on Doppler LIDAR measurements. As shown by the application that has motivated this development, some strongly nonlinear constraints can be guaranteed by the design of the structure. The developed structure is not restricted to the considered application and could be applied successfully to many other feedforward control problems with some prior knowledge of the upcoming disturbances or references.

/pdf/an-unusual-structure-for-a-feedforward-gust-load-alleviation-22ybnnxavo.pdf

An Unusual Structure for a Feedforward Gust Load Alleviation Controller

In this paper, the in-flight remote sensing technologies are considered for two applications: active load alleviation of gust and turbulence and wake impact alleviation. The paper outlines the strong commonalities in terms of sensors and measurement post-processing algorithms and presents also the few differences and their consequences in terms of post-processing. The way the post-processing is being made is detailed before showing results for both applications based on a complete and coupled simulation (aircraft reaction due to disturbances and control inputs during the simulation is influencing the sensor measurements).

In-Flight Remote Sensing and Characterization of Gusts, Turbulence, and Wake Vortices

A flight test campaign for system identification is a costly and time-consuming task. Models derived from wind tunnel experiments and CFD calculations must be validated and/or updated with flight data to match the real aircraft stability and control characteristics. Classical maneuvers for system identification are mostly one-surface-at-a-time inputs and need to be performed several times at each flight condition. Various methods for defining very rich multi-axis maneuvers, for instance based on multisine/sum of sines signals, already exist. A new design method based on the wavelet transform allowing the definition of multi-axis inputs in the time-frequency domain has been developed. The compact representation chosen allows the user to define fairly complex maneuvers with very few parameters. This method is demonstrated using simulated flight test data from a high-quality Airbus A320 dynamic model. System identification is then performed with this data, and the results show that aerodynamic parameters can still be accurately estimated from these fairly simple multi-axis maneuvers.

/pdf/method-for-designing-multi-input-system-identification-1umnyc0h7v.pdf

Nicolas Fezans

Papers

VIRTTAC - A Family of Virtual Test Aircraft for Use in Flight Mechanics and GNC Benchmarks

Robust LPV control design for a RLV during reentry

An Unusual Structure for a Feedforward Gust Load Alleviation Controller

In-Flight Remote Sensing and Characterization of Gusts, Turbulence, and Wake Vortices

Method for designing multi-input system identification signals using a compact time-frequency representation